The next century will bring an increase in frequency and intensity of heat waves, heavy precipitation, hurricanes, droughts, floods, and rising sea levels due to increased greenhouse-gas emissions from fossil-fuel combustion, according a scientific report released on Friday by the United Nations Intergovernmental Panel on Climate Change. The report, prepared by 220 authors from 62 countries, is meant to inform global policymakers in addressing climate change.
The findings strengthen and synthesize the results of many other previous scientific reports, but offer the Nobel Prize-winning U.N. panel’s first comprehensive assessment of the long-term weather impacts of climate change. The release of the 29-page summary of findings for policymakers, which previews the release in February of a longer scientific document, is strategically timed: On Nov. 29, the nations of the world will meet at the annual U.N. climate summit aimed at forging a legally binding global climate-change treaty. Efforts to reach an agreement have been blocked for years as the world’s two biggest greenhouse-gas emitters—the U.S. and China—have failed to agree to policies mandating cuts in fossil-fuel pollution.
The new report also comes at the end of a year of extreme weather: In the U.S. alone, 2011 was a record-breaking year with 14 weather disasters costing over $1 billion each, including the flooding of the Mississippi and Missouri rivers and the extended drought and heat wave in Texas.
Such extreme weather could soon become the norm if emissions are not curbed, the report’s authors warn.
Despite the severity of the warnings, it’s unlikely that the report will have a near-term impact on climate-change policy in the U.S., which is historically the world’s largest emitter of greenhouse gases such as carbon dioxide.
Many Republican lawmakers and presidential candidates—including some who as recently as three years ago strongly advocated taking action on climate change—now question or deny the scientific evidence that global warming is caused by human activity—specifically, by burning coal, oil, and gas.
Scientists say the report is meant to dispel the idea among policymakers that there is scientific uncertainty about the basic tenets of climate change.
“This report is highly relevant to policymaking,” said Rajendra Pauchari, who heads the U.N. climate science panel.
“If we do not give the science … the attention that is likely to bring action then I don’t know if we will see action—and we will continue to see the kind of extreme events described in this report,” he said.